In power distribution networks, there are typically many cable overcurrent protection devices, such as limiters and fuses, that limit and/or even prevent cable damage due to over-current situations that may be caused by circuit overloads, inadvertent short circuit faults and/or the like. The responsible party (such as the utility company) may benefit if they know when these limiting devices operate, e.g., to open the respective electric circuit or link.
Conventional “blown fuse indicators” typically use a small, fusible wire that is electrically connected to a larger, primary fuse element. A spring-loaded flag or other indicia is held in a closed position by the fusible wire. When the fuse element opens a circuit in response to an over-current and/or over-voltage condition, the fusible wire is liquefied, and, consequently, the spring-loaded flag is deployed. However, fusible wires that are electrically integrated with the fuse element and release a spring-loaded indicator may not be easily installed on existing equipment (i.e., retrofitted) and/or may present difficulties with resettability.
It has also been proposed to provide an operation detection device for an overcurrent protection component that need not be electrically integrated with a fuse element. Such devices are described, for example, in co-pending U.S. patent application Ser. No. 12/137,154, filed Jun. 11, 2008, which application is incorporated herein by reference as if set forth in its entirety.
As the power market moves toward the need for more intelligence from the power grid, additional information may be used to monitor the status of the power network system.